Composition and method for visibly reducing the size of skin pores

ABSTRACT

A method for reducing the visible size of facial skin pores by applying a novel composition which comprises an oil absorbing powder, a botanical astringent and a biological compound that alters the structure of the skin and/or the function of the sebaceous glands.

RELATED APPLICATIONS

This is a continuation of application Ser. No. 08/238,978 filed May 6,1994, now U.S. Pat. No. 5,415,861 issued on May 16, 1995, which is acontinuation of application Ser. No. 07/986,814 filed Dec. 8, 1992, nowabandoned, which is a continuation of application Ser. No. 07/724,104filed Jul. 1, 1991, now abandoned.

FIELD OF THE INVENTION

This invention relates to novel topical compositions for visiblyreducing the size of enlarged skin pores, and to a method for usingthese compositions to improve the overall appearance of skin.

BACKGROUND OF THE INVENTION

Human skin is a permeable membrane. It is characterized by thousands ofpores which function as openings for sebaceous (oil producing) andeccrine (sweat-producing) glands located beneath the skin. Each porecommunicates with a corresponding gland by means of a hollow tube,otherwise known as the pilary canal. According to this configuration, apore functions as an exit portal for internally produced sebaceous andsweat gland products such as sebum (oil) and perspiration. Skin poresalso represent entry portals for externally applied substances,including lotions, creams and cosmetic preparations. It is generallyunderstood that human skin represents a changing, dynamic environmentwhere the exit and entry of substances can significantly influence poresize and visibility.

Pores associated with sweat glands are very small. There are noaesthetic considerations because these skin surface openings are notvisible without a magnifying lens. The present invention is directed tothe size and visibility of skin pores that communicate with moretroublesome sebaceous glands. These pores provide the situs for surfaceache which creates a coarse and uneven appearance on the skin.

Skin pores (and sebaceous glands) are large and numerous on the face andscalp, coincidentally the areas of maximum exposure on the skin. Forfacial areas the density ranges from 400 to 800 pores/cm², compared with50 pores/cm² on the arms and legs. The forehead, nose and nasolabialfolds are the areas of highest pore concentration.

Pores, like wrinkles, have a defined size which is susceptible tomeasurement. But; the visual appearance of skin pores partially dependson the texture of surrounding surfaces. A rough, dry condition scatterslight in a manner which emphasizes openings on the skin surface. Incontrast, smooth skin reflects incident light to reduce the appearanceof surface irregularities created by pores or openings. When a pore issurrounded by rough, debris-laden skin it is more noticeable and appearslarger.

In scientific terms, the skin pore of interest is known as a "follicularorifice." The orifice or pore cooperates with a sebaceous folliclecharacterized by a small, hair-producing portion, a deep pilary canaland a multilobular sebaceous gland that secretes its product (sebum or"oil") into the base of the canal.

The upper most portion of the pilary canal is lined with a layer of"horny cells" which are constantly replaced and shed into the canal.Under normal circumstances, the displaced cells mix with sebum thatflows through the canal and onto the skin surface. This dynamic processof descaling and cleansing with sebum occurs on a continuous basis.

Pore size is largely determined by genetic, environmental andphysiological factors. It is generally understood that pore diameter isproportionate to the size of sebaceous glands beneath the skin. A goodcorrelation is recognized between pore size and oil-producing activity.Large pores (orifices) create a coarse, uneven complexion whichgenerally detracts from the appearance of an individual.

Increased pore size is frequently associated with hyperactive sebaceousglands. This condition generates larger amounts of sebum which expandsthe pilary canal and dilates pore diameter to accommodate greaterinternal pressure. By limiting sebum production and/or facilitatingsebum removal, the compositions of the present invention minimize poresize and improve overall appearance.

It will also be appreciated that the sebaceous follicle may producecells which do not shed as fine, discrete particles. When this conditionoccurs, the cells accumulate, coagulate with sebum, mix with other skinmaterials and "plug" the pore opening. This aberration disrupts thenormal environment of cellular shedding and cleansing with sebumsecretions. It also leads to an accumulation of cellular debris,enlargement of the attendant pore and greater visibility on the skinsurface.

The aging process further increases pore size and visibility. Duringadolescence, larger pores are generally attributed to increasedglandular activity and higher sebum production which causes canalblockage and pore expansion. As the aging process continues, sebumproduction gradually declines and the shedding of "horny cells" slowsdown. These conditions cause an accumulation of debris which increasesthe size and visibility of individual pores.

The aging process also causes deterioration of the dermal elementssurrounding the follicle. These changes are manifested by internalcollapse of supporting skin structure and expansion of the follicularcanal. The ultimate result is pore dilation and greater visibility onthe skin surface.

The skin pore reducer of this invention prevents accumulation of oil andother debris in the pilary canal, at the pore opening and on thesurrounding skin surface. This cleansing technique "shrinks" the poreand minimizes visibility on the skin surface.

Numerous art-recognized compositions have attempted to absorb oil andfacial debris from skin surfaces and attendant pore structures. Examplesof these products are described in Groller U.S. Pat. No. 4,933,177 andElliott U.S. Pat. No. 4,954,532. But, the prior art has not identifiedor addressed the multiple causes of skin pore enlargement.

OBJECTS OF THE INVENTION

Accordingly, it is an object of this invention to provide topicallyapplied compositions that reduce the size of visible skin pores.

It is an additional object of the present invention to providecompositions which inhibit the rate of sebum production in the sebaceousfollicles.

It is a further object of the present invention to provide compositionswhich facilitate removal of sebum, oil, dirt and skin debris from poreopenings and surrounding surfaces.

Yet another object of the present invention is to provide compositionswhich enhance dermal matrix qualities directed to elasticity andstructural firmness.

It is a further object of the present invention to provide anover-the-counter formulation which is readily available to the retailconsumer.

Another object of the present invention is to provide a preparedcomposition which can be topically applied without the attention of alicensed physician.

SUMMARY OF THE INVENTION

The present invention provides a method and compositions for reducingthe size of visible skin pores. Active ingredients absorb and remove"oil" (sebum). This cleansing operation temporarily reduces internalpressure which dilates or expands the follicular canal and attendantpore opening.

The described compositions also reduce the cohesion of "horny cells"which are continuously shed into the follicular canal and secreted ontothe skin surface without "plugging" individual pores. Skin debris isloosened and removed from pores and surrounding areas to achievesmoother complexions with smaller, less visible pore structure. Themethod of treatment preferably involves topical application,intermediate drying and removal of effective compositions.

To accomplish these and other benefits, this invention providescompositions which comprise an oil absorbing powder, a botanicalastringent and a biological. Described compositions cleanse skin poreopenings, support the dermal matrix and regulate secretions from thesebaceous glands. By practicing the disclosed method, these compositionscause a visual reduction in the size of skin pores on the face and otherareas of the body.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The novel compositions of this invention comprise three classes ofessential ingredients, preferably in a suitable carrier. The threeclasses are generally defined as oil absorbing powders, botanicalastringents and biologicals that influence the structure of the dermalmatrix and/or the sebaceous glands.

The oil absorbing powder is any substance which is capable of removingoil secretions from a skin pore and its surrounding surface. Exemplaryoil absorbing powders include those made from bentonite, rice starch,silica, calcium sulfate and mixtures thereof. The oil absorbing powderis present in an amount from 10 to 30 wt. %, preferably in an amountfrom 15 to 25 wt. %.

Bentonite is a native, colloidal, hydrated aluminum silicate, otherwiseknown as white clay. As provided commercially, bentonite particlestypically range in size from 1 to 150 μm. Each particle can absorbapproximately one-half its weight in excess oil. Bentonite is apreferred ingredient because it contributes skin softening properties tocompositions of the present invention (Harry, Cosmetic Materials, Vol.2, London, 1950). A particularly useful form is sold under the tradenameMicrofine Bentonite. It is further described in trade literaturedistributed by American Colloid Company, Arlington Heights, Ill.

Rice starch is another preferred oil absorbing powder. Previously, ricestarch was used in cosmetics as a binding agent for face powders. It isprovided by treating rice grains with caustic soda, which dissolves thegluten and precipitates the starch granules. Although rice starch hasbeen known to absorb moisture, we have discovered an unexpected capacityto absorb its full weight in oil. When mixed with glycerin, rice starchhas the added benefit of providing a soothing, protective compositionwhich effectively absorbs oil without overstripping the skin. Theseproperties are described by Greenberg & Lester, Handbook of CosmeticMaterials, Wiley-Interscience, New York, 1954.

Silica is also useful in compositions of the present invention. Thesematerials are commercially available in several grades or particlesizes. Suitable products are sold by Cabot Corporation, Tuscola, Ill.under the trade designation Cab-O-Sil. Cab-O-Sil EH-5 is especiallypreferred with a nominal particle diameter of 0.007 μm and a specificsurface area of approximately 380±30 m² /g. The high surface area isexpected to increase oil absorbency. Conventional testing indicates thatEH-5 can absorb more than four times its weight in skin surface oils.

Like the other oil-absorbing powders of the present invention, effectiveamounts of calcium sulfate remove skin surface oil and withdraw excesssebum from the pilary canal.

Compositions of this invention also include a biological astringent asthe second major component. Botanicals have been used topically andsystemically for over 5,000 years. Anticipated medicinal benefits werehistorically based on folklore. But, modern analytical techniques nowidentify constituent compounds and provide scientific explanations forrelated benefits to the dermal matrix.

According to the present invention, representative botanical astringentsinclude extracts from herbs such as Horsetail, Witch Hazel, St. John'sWort, Balm Mint and Linden. Mixtures of these extracts are alsocontemplated. The botanical is present in an amount from 0.01 to 10 wt.%, preferably in an amount from 0.1 to 1.0 wt. %.

Witch Hazel (Hamamelis virginiana) extracts have art-recognizedastringent and cleansing properties which are useful for cosmeticpreparations. The astringent effect is provided by a relatively high(8-12%) concentration of tannins found in the leaves and bark. WitchHazel extracts also contain saponins, a sugar-steroid alcohol complexwhich exhibits high surface activity. This property improves shecleansing function and facilitates removal of dirt, oil and debris fromskin pores and surrounding surfaces.

Another astringent botanical extract is derived from Linden (Tiliaplatyphyllos). Linden extracts contain several constituents responsiblefor immediate and long-term benefits in the treatment of oily skin andlarge pores. Tannins, citral and a complex mixture of fatty oils provideimmediate astringent and cleansing benefits.

Long-term benefits are derived from the Vitamin C, Vitamin E andfarnesol content in Linden extracts. Farnesol is a precursor tosqualene, a normal product of the sebaceous glands. An increasedconcentration of farnesol can be expected to moderate sebum sec-retions.Vitamin C is essential to the production of collagen, a criticalcomponent of the dermal matrix. Vitamin E is an anti-oxidant for thecollagen matrix. This anti-oxidant function is enhanced by thesynergistic effect of Vitamin C present in the extract. By protectingthe quality of the dermal matrix, Linden extracts improve skin textureand reduce the size of visible skin pores. See, e.g., Kaplan, "A NewStabilized Ascorbic Acid Solution: Percutaneous Absorption and Effect onRelative Collagen Synthesis," J. Cutaneous Aging & Cosmetic Dermatology,Vol. 1, No. 2, pp. 115-121 (1988/1989); Tojo, "Skin Penetration ofVitamins C and E," J. Soc. Cosmet. Chem., Vol. 40, pp. 119-125(March/April 1989).

St. John's Wort (Hypericum performatum) is a suitable cosmeticastringent based on relatively high concentrations of tannins in theextract. The botanical also contains the Bioflavonoid rutin, a naturallyoccurring anti-oxidant. Significant amounts of Vitamin A are present tosuppress sebum production and reduce the size of large skin pores.Vitamin C concentrations provide the same beneficial propertiesdescribed in connection with Linden extracts.

Extract from Balm Mint (Melissa officinalis) offers similar astringentproperties based on the presence of tannins and citral as principalconstituents. This extract also contains Bioflavinoids which protect thedermal matrix and provide previously described advantages.

Horsetail extract (Equisetum arvense) is a preferred compound because itcontains significant amounts (>8%) of organic silicones. These siliconesare known to regulate collagen cross-linking and improve the structuralframework of connective tissues in the skin. Like the alternativecompositions, Horsetail extract functions on and below the skin surfaceto reduce pore size with regular application.

Active biologicals are the third essential component of the presentinvention. Specific materials are selected for their ability tonormalize and regulate sebum production. These biologicals also free thepilary canal of pore-clogging dirt and skin debris. By way ofillustration, representative biologicals include salicylic acid,farnesyl acetate, panthethine triacetate, pyridoxine hydrochloride,biotin, lysine carboxymethyl cisteinate and mixtures thereof. Thebiological compound is present in an amount from 0.01 to 10 wt. %,preferably in an amount of from 0.05 to 0.5 wt. %.

Pyridoxine HCl is an interchangeable form of Vitamin B₆, a preferreddietary supplement not synthesized by the human body. Although not wellunderstood, it is anticipated that Vitamin B₆ deficiencies causeincreased production of fatty acids in the sebaceous gland which enlargethe pilary canal and corresponding skin pore. Empirical observationsindicate that skin supplementation of Vitamin B₆ (pyridoxine HCl)reduces sebum production and limits pore size.

Recent evidence also suggests that pyridoxine plays an important role incollagen and elastin cross-linking. Roe, Nutrition and the Skin, Alan R.Liss, Inc., 1986. Proper cross-linking of these proteins influences thequality of the dermal matrix as previously described. A pyridoxinedeficiency reduces cross-linking and increases pore size bydestabilizing the skin structure.

Another preferred biological is biotin, a water-soluble B vitamin.Biotin deficiencies reportedly cause seborrheic dermatitis. It is alsoreported that Biotin acts synergistically with Vitamin B₆ to maintainnormal fatty acid synthesis and regulate sebum production. d-Biotin isotherwise expressed asCis-hexahydro-2-oxo-1H-thieno-(3,4)-imidazole-4-valeric acid. Suitablecompounds are available from Hoffmann-La Roche Inc., Roche ChemicalDivision, Nutley, N.J.

Salicylic acid is an alternative biological which accelerates theremoval of horny cells by decreasing their "stickiness" or cohesion.See, Roberts, "Detection of the Action of Salicylic Acid on the NormalStratum Corneum," Brit. J. Derm., Vol. 103, page 191 (1980). It will beappreciated that skin pores are smaller in appearance following theremoval of horny cells from the pore opening and surrounding skinsurface.

Farnesyl acetate and panthenyl triacetate form a unique bioactivecomplex which regulates secretions from the sebaceous glands. Farnesoland farnesol derivatives are naturally occurring substances which act asprecursors and intermediates in the biosynthesis of squalene andsterols, specifically cholesterol. Additional disclosure is provided byInduchem Technical Bulletin, "Unitrienol T-27," Induchem AG Dubendorf,Germany. Squalene and cholesterol are produced only by the sebaceousglands, and controlling their rate of production is critical toregulating overall sebum production.

Lysine carboxymethyl cisteinate is a carefully balanced complex whichregulates sebum secretions as shown by clinical demonstrations. Whilethe mechanism for this action is not completely understood, reduced poresize has been observed following use of treatment products containingthis active ingredient.

According to the present invention, the oil absorbing powder, botanicalextract and biological compound are admixed with a suitable vehicle orcarrier system. Preferred carriers include water, ethyl alcohol,isopropyl alcohol, glycerin and mixtures thereof which are present inconcentrations sufficient to dissolve and/or disperse the variouscomponents. A suitable delivery system will preferably dry in areasonably short period of time (15-20 minutes maximum). It should bewater-soluble and easily removed by rinsing.

It will be appreciated that a topical delivery system may includelotions, ointments, salves, creams, gels, foams, sprays and the like.Physical carriers may also take the form of patches or masks which areknown in the art. Further additions are contemplated provided that theyare compatible with the active ingredients and do not adversely affectthe desired function. Additional components may include well-knowncolorants, fragrances, thickeners, Preservatives, humectants,surfactants, dispersants and the like,

The invention will now be further described with reference to thefollowing broad example which is provided for illustrative, not limitingpurposes.

    ______________________________________                                                            % (w/w)                                                   ______________________________________                                        demineralized water   q.s.                                                    glycerin              5.0                                                     alcohol               13.0                                                    thickener             0.5                                                     surfactants           3.0                                                     oil absorbing powder  21.0                                                    botanical extract(s)  0.5                                                     biological             0.212                                                  colorant(s)/fragrance/preservative                                                                  q.s.                                                    ______________________________________                                    

The abbreviation "q.s." is standard dispensing nomenclature which means"as needed" or "as sufficient." During practical application, water,colorants, fragrances, preservatives and the like are added to thecomposition for cosmetic and/or aesthetic purposes. For example,viscosity can be varied with the amount of water. A viscous compositionwill dry faster based on reduced water content. Higher alcoholconcentrations will also accelerate the drying or evaporation process.

The novel method of the present invention is practiced by applying adescribed composition to the face (or other skin surface), allowing theapplied composition to dry completely and rinsing or otherwise removingthe dried composition from the skin surface, preferably with water.

The composition is generally formulated to dry within 15-20 minutes.When applied as a mask, the preferred composition dries in approximately15 minutes, as indicated by a distinct color change. After a singleapplication pore size is visibly reduced and the skin displays asmoother, more refined texture. Regular applications will maintain thesepreferred characteristics.

This specification clearly illustrates the principles of the presentinvention. Based on this disclosure, numerous modifications will bereadily apparent to those skilled in the art. These modifications arewithin the scope and spirit of the present invention as defined by thefollowing claims.

What is claimed is:
 1. A composition for visibly reducing the size ofskin pores, consisting essentially of:10 to 30 wt. % of an oil absorbingpowder having an average particle size of less than 1.0 μm, said powderselected from the group consisting of silica, rice starch, bentonite,calcium sulfate and mixtures thereof; 0.01 to 10 wt. % of a botanicalastringent selected from the group consisting of an extract fromEquisetum arvense, Hamamelis, vaginiana, Hypericum performatum, Melissaofficinalis, Tilia platyphyllos and mixtures thereof; 0.01 to 10 wt. %of a biological compound capable of regulating sebum production andclearing pilary canals, said compound selected from the group consistingof salicylic acid, farnesyl acetate, panthetine triacetate, pyridoxinehydrochloride, biotin, lysine carboxymethyl cisteinate and mixturesthereof; and a topically acceptable carrier.
 2. The composition of claim1, further consisting of at least one additive selected from the groupconsisting of colorants, fragrances, preservatives, thickeners,humectants and mixtures thereof.
 3. The composition of claim 1, whereinsaid topically acceptable carrier is selected from the group consistingof water, ethyl alcohol, isopropyl alcohol, glycerin and mixturesthereof.
 4. The composition of claim 1, further consisting a topicaldelivery system for said composition, said delivery system selected fromthe group consisting of lotions, ointments, creams, gels, foams, sprays,patches and masks.
 5. The composition of claim 1, wherein said oilabsorbing powder is 15 to 25 wt. % of said composition.
 6. Thecomposition of claim 1, wherein said botanical astringent is 0.05 to 1.0wt. % of said composition.
 7. The composition of claim 1, wherein saidbiological compound is 0.05 to 0.5 wt. % of said composition.